Would go with ghost ring, only 50 sounds like a deal, I have looked through these and found them second only to MMC Ghost ring sights, MMC installed typicaly costs 250.00 (4340 steel and very heavy duty but a pretty penny.) I'm having them added to benneli (factory ring is in the canyon near my house--blew off in fast 3" mag string),and 870, but would like to add the 590a1 with factory rings to my colleciton later.